Preparation for Common Test

Headline: Preparation for Common Test.

Well, for today's lesson, we went through worksheets again so as to prepare us for the coming common test and correct the mistakes we had made.

I have learnt that the part of an atom which contains the protons and neutrons is called nucleon. The nucleon is positively charged and is densely concentrated in the centre of an atom.

I have also learnt that atoms usually gain or lose electrons but not the protons and neutrons as the protons and neutrons are found in the inner area of the atom. Thus, the electrons will be easier to be attracted by other atoms than the subatomic particles found in the inner area.

I learnt that the similarity between sulfur molecule and sulfur dioxide molecule is that both molecules are made up of more than one atom. As for their difference is that sulfur molecule contains one type of atoms but sulfur dioxide molecule has more than one type of atoms.

(Example of an atom. Inner part, nucleon - consists of protons and neutrons. Outer part - electrons orbiting in electron shells)



Sources: Google Images

Quiz

Headline: Quiz.

We did a quiz today so as to check on our understanding on the topic, Atoms & Molecules.

I have learnt that when a question asks us about the number of subatomic particles in an atom of XXX, we should list out the number of protons, electrons and neutrons but not the total number of subatomic particles in it. For example, if a question asks us about the number of subatomic particles in an atom of boron with a nucleon number of 10, we should not answer that the number of subatomic particles in an atom is 15. Instead, we should answer that there are 5 protons, 5 electrons and 5 neutrons.

I have also learnt that atoms form ions as atoms react when they are forming compounds. They tend to lose or gain electrons so as to get the electronic configuration of a noble gas.

(An example of a key in the periodic table)         



Sources: Google Images

Worksheets

For today's Science lesson, we went through some worksheets and we were allowed to raise queries on the concepts which we did not understand.

3 Thoughts:
1) I have learnt that the similarities between an atom and an ion are that both of them have the same number of protons, neutrons and electron shells. As for the difference, an atom is neutral while an ion has a net charge (positive/negative).
2) I have also learnt that the difference between an oxygen atom and an oxygen molecule is that the oxygen atom has one atom but the oxygen molecule has several. As for their similarity, they both contain an oxygen atom.
3) I learnt that a mixture and a molecule of compound are different from one another. A mixture consists of different kinds of atoms mixed together. While a molecule of compound contains different kinds of atoms chemically combined together.

2 Questions:
1) Is it still considered a mixture when there is a presence of a mixture of atoms and molecules of element?
2) When the same kind of atoms mixed together, is it called a mixture or an element?

1 Useful application:
1) By clarifying all the misconceptions that we had, we are able to score better in our tests or examinations.

More on Molecules

Today, we went through some worksheets and revised on the topic, Atoms and Molecules. Well, we focused more on molecules for this lesson.

I used to think that a molecule is an atom that stands by itself. But now I think that a molecule is actually made up of two or more atoms chemically combined together.

I also used to think that there is only one type of molecules. Now, I think that there are two types of molecules. One type is molecules of elements while the other type is molecules of compounds. Molecules of elements consist of a fixed number of same type of atoms chemically combined together. This type of molecules is called diatomic molecules. As for molecules of compounds, they are made up of a fixed number of different types of atoms chemically combined together.

There is also a chemical formula to represent a compound. The formula tells us about the types of atoms present in the compound and the ratio of different atoms found in the compound.

(Top - Molecules of Elements. Bottom - Molecules of Compounds)

Sources: Google Images

First Class Test

Headline: First Class Test.

Today, we had our first class test and it is on the topic, Particulate Model of Matter.

I have learnt that when an element has good electrical conductivity and has the highest melting point, it will have the strongest forces of attraction between its particles. This is because the heat supplied will have a hard time overcoming the forces of attraction between the particles and therefore, having the highest melting point. However, does the density of the element affect the forces of attraction between the particles?

I have also learnt that when an iron nail is dropped into a glass of water, it sinks to the bottom of the glass. This is because an iron nail is a solid in which their particles are arranged in a fixed, regular pattern and are packed very closely together. But the particles of water are arranged in a disorderly pattern. Thus, the iron nail of a fixed mass and a smaller volume has a higher density than water.

Ions

Today, we learnt about ions and how they are formed.

3 Thoughts:
1) An ion is formed when an atom loses of gains electrons. Hence, in an ion, there is an imbalance in the number of protons and electrons.
2) A neutral atom can gain or lose electrons through chemical reaction. When an atom loses electrons, it will be positively charged, also known as cations. When an atom gains electrons, it will be negatively charged, called anions. Elements in the same group of periodic table will form ions of the same charge.
3) Atoms of metals tend to lose electrons while atoms of non-metals tend to gain electrons. Atoms form ions so as to achieve a noble gas (duplet or octet) structure.

2 Questions:
1) Will an atom lose or gain too much electrons?
2) Will there be a case where atoms of metals gain electrons?

1 Useful application:
1) When we know more about ions, we will be able to know what chemical changes/properties the elements are undergoing/have.

(Example of how atoms lose or gain electrons)

Sources: Google Images

Atoms and Molecules

For today's Science lesson, we went through the concepts on atoms and molecules which we had learnt last year. Then, we went deeper into the topic and gained many new concepts.

3 Thoughts:
1) Atoms contain electrons which they move around the nucleus in regions called electron shells. The more the electrons, the more electron shells an atom has. In addition, only a certain number of electrons move in each of the electron shells. For example, the first shell which is nearest to the nucleus can only hold a maximum of 2 electrons. While the second and third electron shells can each holds a maximum of 8 electrons.
2) The arrangement of the electrons, also known as electronic configuration or electronic structure, is very important as it determines the chemical properties of the atom and we are able to know what changes the element will go through.
3) We had also learnt how to draw electronic structures by using cross or dot to represent each electron. The cross or dot must always be placed opposite each other, like East to West or North to South.

2 Questions:
1) Do all the electrons in the electron shells move in the same way (e.g. clockwise direction)?
2) Why is it only that the inner most of the electron shells can only hold 2 electrons?

1 Useful application:
1) By knowing the arrangement of the electrons in an atom, we are able to know the way how elements are placed in the periodic table.

(Example of an electronic structure of an atom)



Sources: Google Images